This invention relates to polyphosphazene copolymers containing repeating ##STR2## units in the polymer chain in which alkyl borate substituents and substituted and unsubstituted alkoxy, aryloxy, amino or mercapto substituents are attached to the phosphorus atom. More particularly, the invention relates to polyphosphazene copolymers containing substituents derived from alkyl borate and substituted or unsubstituted aliphatic or aromatic alcohols, amino compounds and mercaptan compounds.
Polyphosphazene copolymers containing repeating ##STR3## units in which various alkoxy, substituted alkoxy, aryloxy and substituted aryloxy groups are attached to the phosphorus atom and their method of preparation are described in the prior art as illustrated in the publication "Phosphorus-Nitrogen Compounds," Academic Press, New York, N.Y. 1972 by H. R. Allcock and "Poly(Organophosphazenes)," Chemtech, Sept. 19, 1975 by H. R. Allcock and in such U.S. Pat. Nos. as 3,515,688; 3,702,833; and 3,856,712.
However, none of the prior art of which applicants are aware, discloses or suggests polyphosphazene copolymers containing alkyl borate substituents attached to the phosphorus atom or methods of preparing such copolymers.